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Haslam TM, Kunst L. Arabidopsis ECERIFERUM2-LIKEs Are Mediators of Condensing Enzyme Function. PLANT & CELL PHYSIOLOGY 2021; 61:2126-2138. [PMID: 33079186 DOI: 10.1093/pcp/pcaa133] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Condensing enzymes catalyze the committed reaction of fatty acid elongation and determine the chain length of fatty acids accepted and produced by the elongation complex. While necessary for the elongation of very-long-chain fatty acids (VLCFAs), identified plant condensing enzymes cannot efficiently produce VLCFAs longer than 28 carbons, which are precursors for the most abundant cuticular waxes of most plant species that have been surveyed. The eceriferum2 (cer2) mutant of Arabidopsis thaliana has a severe wax-deficient phenotype and specifically lacks waxes longer than 28 carbons, but the CER2 protein does not share sequence similarity with condensing enzymes. Instead, CER2 is homologous to BAHD acyltransferases. Heterologous expression in yeast previously demonstrated that CER2, and a small clade of BAHD acyltransferases with high sequence identity to CER2, can extend the chain-length specificity of the condensing enzyme CER6. This biochemical function is distinct from that of the broader BAHD acyltransferase family. The product specificity and physiological functions of individual CER2-LIKE proteins are unique. Here, we demonstrate that CER2 physically interacts with the fatty acid elongase. We cloned chimeric CER2-LIKE proteins and expressed these in yeast cells to identify the features that define the substrate specificities of CER2-LIKEs. We generated homology-based structural models to compare CER2-LIKEs and BAHD acyltransferases. In addition, based on the current phylogenetic analysis of the CER2-LIKE clade, we describe two further Arabidopsis CER2-LIKE genes, CER2-LIKE3 and CER2-LIKE4. We used yeast expression and mutant analysis to characterize these genes. Collectively, these results expand our knowledge of the functions of CER2-LIKEs, the BAHD acyltransferase family and cuticular wax metabolism.
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Affiliation(s)
- Tegan M Haslam
- Department of Botany, University of British Columbia, Vancouver V6T 1Z4, BC, Canada
| | - Ljerka Kunst
- Department of Botany, University of British Columbia, Vancouver V6T 1Z4, BC, Canada
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Haslam TM, Kunst L. Extending the story of very-long-chain fatty acid elongation. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2013; 210:93-107. [PMID: 23849117 DOI: 10.1016/j.plantsci.2013.05.008] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 05/01/2013] [Accepted: 05/03/2013] [Indexed: 05/18/2023]
Abstract
Very-long-chain fatty acids (VLCFAs) are essential molecules produced by all plant cells, and are components or precursors of numerous specialized metabolites synthesized in specific cell types. VLCFAs are elongated by an endoplasmic reticulum-localized fatty acid elongation complex of four core enzymes, which sequentially add two carbon units to a growing acyl chain. Identification and characterization of these enzymes in Arabidopsis thaliana has revealed that three of the four enzymes act as generalists, contributing to all metabolic pathways that require VLCFAs. A fourth component, the condensing enzyme, provides substrate specificity and determines the amount of product synthesized by the entire complex. Land plants have two families of condensing enzymes, FATTY ACID ELONGATION 1 (FAE1)-type ketoacyl-CoA synthases (KCSs) and ELONGATION DEFECTIVE-LIKEs (ELO-LIKEs). Our current knowledge of the specific roles of different condensing enzymes is incomplete, as is our understanding of the biological function of a recently characterized family of proteins, CER2-LIKEs, which contribute to condensing enzyme function. More broadly, the stoichiometry and quaternary structure of the fatty acid elongase complex remains poorly understood, and specific phylogenetic and biochemical questions persist for each component of the complex. Investigation of VLCFA elongation in different organisms, structural biochemistry, and cell biology approaches stand to greatly benefit this field of plant biology.
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Affiliation(s)
- Tegan M Haslam
- Department of Botany, University of British Columbia, 3529-6270 University Boulevard, Vancouver, BC, Canada
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3
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Zhou Y, Grice K, Stuart-Williams H, Farquhar GD, Hocart CH, Lu H, Liu W. Biosynthetic origin of the saw-toothed profile in delta(13)C and delta(2)H of n-alkanes and systematic isotopic differences between n-, iso- and anteiso-alkanes in leaf waxes of land plants. PHYTOCHEMISTRY 2010; 71:388-403. [PMID: 20056262 DOI: 10.1016/j.phytochem.2009.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 11/19/2009] [Accepted: 11/19/2009] [Indexed: 05/28/2023]
Abstract
The n-fatty acids containing an even number of carbons (ECN-n-FAs) in higher plants are biosynthesised by repetitive addition of a two carbon unit from malonyl-ACP. The n-alkanes containing an odd number of carbon atoms (OCN-n-alkanes) are generally formed by the decarboxylation of ECN-n-FAs, but it is unknown how the less abundant even-carbon-numbered alkanes (ECN-n-alkanes) are biosynthesised in higher plants. There is a distinctive compositional pattern of incorporation of stable carbon ((13)C) and hydrogen ((2)H) isotopes in co-existing ECN- and OCN-n-alkanes in leaves of higher plants, such that the OCN n-alkanes are relatively enriched in (13)C but relatively depleted in (2)H against the ECN-n-alkanes. This is consistent with the OCN-n-fatty acids having a propionate precursor which is derived from reduction of pyruvate. A tentative pathway is presented with propionate produced by enzymatic reduction of pyruvate which is then thio-esterified with CoSH (coenzyme A thiol) in the chloroplast to form the terminal precursor molecule propionyl-CoA. This is then repetitively extended/elongated with the 2-carbon unit from malonyl-ACP to form the long chain OCN-n-fatty acids. The anteiso- and iso-alkanes in Nicotiana tabacum leaf waxes have previously been found to be systematically enriched in (13)C compared with the n-alkanes by Grice et al. (2008). This is consistent with the isotopic composition of their putative respective precursors (pyruvate as precursor for n-alkanes, valine for iso-alkanes and isoleucine for anteiso-alkanes). The current study complements that of Grice et al. (2008) and looks at the distribution of hydrogen isotopes. The n-alkanes were found to be more enriched in deuterium ((2)H) than the iso-alkanes which in turn were more enriched than the anteiso-alkanes. We propose therefore that the depletion of (2)H in the iso-alkanes, relative to the n-alkanes is the consequence of accepting highly (2)H-depleted hydrogen atoms from NADPH during their biosynthesis. The anteiso-alkanes are further depleted again because there are three NADPH-derived hydrogen atoms in their precursor isoleucine, as compared with only one NADPH-derived hydrogen in valine, the precursor of the iso-alkanes.
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Affiliation(s)
- Youping Zhou
- RSB, Australian National University, Canberra, ACT 2601, Australia.
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4
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Delaney B, Appenzeller LM, Munley SM, Hoban D, Sykes GP, Malley LA, Sanders C. Subchronic feeding study of high oleic acid soybeans (Event DP-3Ø5423-1) in Sprague-Dawley rats. Food Chem Toxicol 2008; 46:3808-17. [PMID: 18952136 DOI: 10.1016/j.fct.2008.10.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2008] [Revised: 09/30/2008] [Accepted: 10/01/2008] [Indexed: 11/26/2022]
Abstract
DP-3Ø5423-1 (305423) is a genetically-modified (GM) soybean that was produced by biolistic insertion of a gm-fad2-1 gene fragment and the gm-hra gene into the germline of soybean seeds. The gm-fad2-1 gene fragment cosuppresses expression of the endogenous FAD2-1 gene encoding the seed-specific omega-6 fatty acid desaturase resulting in higher concentrations of oleic acid (18:1) relative to linoleic acid (18:2). The gm-hra gene encoding a modified acetolactate synthase (ALS) enzyme was used as a selectable marker. In the current study, processed fractions (meal, hulls, and oil) from 305423 soybeans, non-GM soybeans with a similar genetic background (near isoline control) and three commercially-available non-GM varieties were used to formulate diets that were nutritionally comparable to PMI Certified Rodent LabDiet 5002. Diets were fed to young adult Crl:CD(SD) rats (12/sex/group) for approximately 90 days. Compared with rats fed the non-GM control diet, no biologically relevant differences were observed in rats fed the 305423 diet with respect to body weight/gain, food consumption/efficiency, mortality, clinical signs of toxicity, or ophthalmological observations. No test diet-related effects were observed on neurobehavioral assessments, organ weights, or clinical or anatomic pathology. These results demonstrated that 305423 soybeans are as safe and wholesome as non-GM soybeans.
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Affiliation(s)
- Bryan Delaney
- Pioneer, A DuPont Company, Pioneer Hi-Bred International Inc., Johnston, IA 50131-0552, USA.
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5
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Liang G, Cline GW, Macica CM. IGF-1 stimulates de novo fatty acid biosynthesis by Schwann cells during myelination. Glia 2007; 55:632-41. [PMID: 17299765 DOI: 10.1002/glia.20496] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Schwann cell (SC) differentiation to the myelinating phenotype is characterized by the elaboration of a lipid-rich membrane and the expression of myelin-specific proteins. Insulin-like growth factor-1 (IGF-1) has been identified as a growth factor that stimulates the early events of myelination in SCs that signals via the PI3K/Akt pathway. Given the role of IGF-1 in promoting myelination, we performed studies to determine if the fatty acid biosynthetic pathway was a target of IGF-1 signaling in the formation of myelin membrane in dorsal root ganglion neuron/Schwann cell (DRG/SC) cocultures. We report that the fatty acid profile of lipid extracts of cocultures treated with IGF-1 match that reported for native myelin membrane by electrospray mass spectroscopy analysis. We also demonstrate de novo fatty acid biosynthesis in response to IGF-1 treatment in DRG/SC cocultures metabolically labeled with (13)C-acetate as a carbon source for fatty acid synthesis. Consistent with this finding, Western blot analysis of lysates from both cocultures and purified SCs reveal that IGF-1 stimulates two key fatty acid synthesizing enzymes. Additionally, we show that stimulation of fatty acid synthesizing enzymes is mediated by the PI3K/Akt signaling pathway. We also show that the fatty acid synthesizing enzymes and associated signaling pathways are elevated during the period of myelin membrane formation in sciatic nerve. Collectively, these findings demonstrate that IGF-1 plays an important regulatory function during myelin membrane formation.
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Affiliation(s)
- Guoying Liang
- Division of Endocrinology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8020, USA
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Puyaubert J, Dieryck W, Costaglioli P, Chevalier S, Breton A, Lessire R. Temporal gene expression of 3-ketoacyl-CoA reductase is different in high and in low erucic acid Brassica napus cultivars during seed development. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1687:152-63. [PMID: 15708363 DOI: 10.1016/j.bbalip.2004.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 11/15/2004] [Accepted: 11/19/2004] [Indexed: 10/26/2022]
Abstract
The membrane-bound acyl-CoA elongase complex is a key enzyme responsible for erucoyl-CoA synthesis. Among the four putative genes encoding the four moieties of this complex in Brassica napus seeds, only one has been characterized, the Bn-fae1 gene, which encodes the 3-ketoacyl-CoA synthase. The genes encoding the other enzymes (3-ketoacyl-CoA reductase, 3-hydroxyacyl-CoA dehydratase and trans-2,3-enoyl-CoA reductase) have not been identified. We cloned two 3-ketoacyl-CoA reductase cDNA isoforms, Bn-kcr1 and Bn-kcr2, from B. napus seeds. Their function was identified by heterologous complementation in yeast by restoring elongase activities. The comparison of Bn-kcr mRNA expression in different B. napus tissues showed that the genes were preferentially expressed in seeds and roots. We also investigated the regulation of gene expression in High Erucic Acid Rapeseed (HEAR) and in Low Erucic Acid Rapeseed (LEAR) cultivars during seed development. The co-expression of Bn-fae1 and Bn-kcr observed in HEAR cultivar during seed development was different in LEAR cultivar, suggesting that expression of both genes was directly or indirectly linked.
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Affiliation(s)
- Juliette Puyaubert
- Laboratoire de Biogenèse Membranaire, CNRS FRE 2694, Université V. Segalen Bordeaux 2, 146, Rue Léo Saignat, 33076 Bordeaux Cedex, France
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7
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Xu X, Dietrich CR, Lessire R, Nikolau BJ, Schnable PS. The Endoplasmic reticulum-associated maize GL8 protein is a component of the acyl-coenzyme A elongase involved in the production of cuticular waxes. PLANT PHYSIOLOGY 2002; 128:924-34. [PMID: 11891248 PMCID: PMC152205 DOI: 10.1104/pp.010621] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2001] [Revised: 09/21/2001] [Accepted: 11/27/2001] [Indexed: 05/18/2023]
Abstract
The gl8 gene is required for the normal accumulation of cuticular waxes on maize (Zea mays) seedling leaves. The predicted GL8 protein exhibits significant sequence similarity to a class of enzymes that catalyze the reduction of a ketone group to a hydroxyl group. Polyclonal antibodies raised against the recombinant Escherichia coli-expressed GL8 protein were used to investigate the function of this protein in planta. Subcellular fractionation experiments indicate that the GL8 protein is associated with the endoplasmic reticulum membranes. Furthermore, polyclonal antibodies raised against the partially purified leek (Allium porrum) microsomal acyl-coenzyme A (CoA) elongase can react with the E. coli-expressed GL8 protein. In addition, anti-GL8 immunoglobulin G inhibited the in vitro elongation of stearoyl-CoA by leek and maize microsomal acyl-CoA elongase. In combination, these findings indicate that the GL8 protein is a component of the acyl-CoA elongase. In addition, the finding that anti-GL8 immunoglobulin G did not significantly inhibit the 3-ketoacyl-CoA synthase, 3-ketoacyl-CoA dehydrase, and (E) 2,3-enoyl-CoA reductase partial reactions of leek or maize acyl-CoA elongase lends further support to our previous hypothesis that the GL8 protein functions as a beta-ketoacyl reductase during the elongation of very long-chain fatty acids required for the production of cuticular waxes.
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Affiliation(s)
- Xiaojie Xu
- Laboratoire de Biogenese Membranaire, Centre National de la Recherche Scientifique UMR 5544, Universite V. Segalen, Bordeaux 2, 146, 33076 Bordeaux cedex
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9
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Murphy DJ, Mukherjee KD. Biosynthesis of very long chain monounsaturated fatty acids by subcellular fractions of developing seeds. FEBS Lett 2001. [DOI: 10.1016/0014-5793(88)80650-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Domergue F, Chevalier S, Santarelli X, Cassagne C, Lessire R. Evidence that oleoyl-CoA and ATP-dependent elongations coexist in rapeseed (Brassica napus L.). EUROPEAN JOURNAL OF BIOCHEMISTRY 1999; 263:464-70. [PMID: 10406955 DOI: 10.1046/j.1432-1327.1999.00520.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The elongation of different substrates was studied using several subcellular fractions from Brassica napus rapeseed. In the presence of malonyl-CoA, NADH and NADPH, very-long-chain fatty acid (VLCFA) synthesis was observed from either oleoyl-CoA (acyl-CoA elongation) or endogenous primers (ATP-dependent elongation). No activity was detected using oleic acid as precursor. Acyl-CoA and ATP-dependent elongation activities were mainly associated with the 15 000 g/25 min membrane fraction. Reverse-phase TLC analysis showed that the proportions of fatty acids synthesized by these activities were different. Acyl-CoA elongation increased up to 60 microM oleoyl-CoA, and ATP-dependent elongation was maximum at 1 mM ATP. Both activities increased with malonyl-CoA concentration (up to 200 microM). Under all conditions tested, acyl-CoA elongation was higher than ATP-dependent elongation, and, in the presence of both ATP and oleoyl-CoA, the elongation activity was always lower. ATP strongly inhibited acyl-CoA elongation, whereas ATP-dependent elongation was slightly stimulated by low oleoyl-CoA concentrations (up to 15 microM) and decreased in the presence of higher concentrations. CoA (up to 150 microM) had no effect on the ATP-dependent elongation, whereas it inhibited the acyl-CoA elongation. These marked differences strongly support the presence in maturing rapeseed of two different elongating activities differently modulated by ATP and oleoyl-CoA.
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Affiliation(s)
- F Domergue
- Laboratoire de Biogenèse Membranaire, Université Victor Segalen Bordeaux 2, France Ecole Supérieure de Technologie des Biomolécules de Bordeaux (ESTBB), Université Victor Segalen Bordeaux 2, France
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11
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Barrett PB, Harwood JL. Characterization of fatty acid elongase enzymes from germinating pea seeds. PHYTOCHEMISTRY 1998; 48:1295-304. [PMID: 9720312 DOI: 10.1016/s0031-9422(97)00669-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In vitro biosynthesis of radioactive arachidate and behenate was observed when microsomal fractions of germinating pea seeds were incubated with exogenous stearoyl-CoA (18:0-CoA) or arachidoyl-CA (20:0-CoA) in the presence of NADPH, [2-14C]malonyl-CoA and ATP. Characterization of parameters required for optimal stearoyl- and arachidoyl-CoA elongation revealed that, at least, two chain-length-specific elongases are necessary for very-long-chain fatty acid synthesis. Both enzymes were found to be sensitive to the group-selective reagents, p-CMB, NEM, iodoacetate, arsenite and phenylglyoxal. Subcellular fractionation studies indicated that both of these elongases were localized mainly in the endoplasmic reticulum.
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Affiliation(s)
- P B Barrett
- School of Molecular and Medical Biosciences, University of Wales Cardiff, U.K
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12
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Rhee Y, Hlousek-Radojcic A, Ponsamuel J, Liu D, Post-Beittenmiller D. Epicuticular wax accumulation and fatty acid elongation activities are induced during leaf development of leeks. PLANT PHYSIOLOGY 1998; 116:901-11. [PMID: 9501123 PMCID: PMC35092 DOI: 10.1104/pp.116.3.901] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/1997] [Accepted: 11/14/1997] [Indexed: 05/18/2023]
Abstract
Epicuticular wax production was evaluated along the length of expanding leek (Allium porrum L.) leaves to gain insight into the regulation of wax production. Leaf segments from the bottom to the top were analyzed for (a) wax composition and load; (b) microsomal fatty acid elongase, plastidial fatty acid synthase, and acyl-acyl carrier protein (ACP) thioesterase activities; and (c) tissue and cellular morphological changes. The level of total wax, which was low at the bottom, increased 23-fold along the length of the leaf, whereas accumulation of the hentriacontan-16-one increased more than 1000-fold. The onset of wax accumulation was not linked to cell elongation but, rather, occurred several centimeters above the leaf base. Peak microsomal fatty acid elongation activity preceded the onset of wax accumulation, and the maximum fatty acid synthase activity was coincident with the onset. The C16:0- and C18:0-ACP-hydrolyzing activities changed relatively little along the leaf, whereas C18:1-ACP-hydrolyzing activity increased slightly prior to the peak elongase activity. Electron micrographic analyses revealed that wax crystal formation was asynchronous among cells in the initial stages of wax deposition, and morphological changes in the cuticle and cell wall preceded the appearance of wax crystals. These studies demonstrated that wax production and microsomal fatty acid elongation activities were induced within a defined and identifiable region of the expanding leek leaf and provide the foundation for future molecular studies.
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Affiliation(s)
- Y Rhee
- Plant Biology Division, The Samuel Roberts Noble Foundation, P.O. Box 2180, Ardmore, Oklahoma 73402, USA
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13
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Abstract
The aerial surfaces of plants are covered with a wax layer that is primarily a waterproof barrier but that also provides protection against environmental stresses. The ubiquitous presence of cuticular wax is testimony to its essential function. Genetic and environmental factors influence wax quantity and composition, which suggests that it is an actively regulated process. The basic biochemistry of wax production has been elucidated over the past three decades; however, we still know very little about its regulation. This review presents a discussion along with new perspectives on the regulatory aspects of wax biosynthesis. Among the topics discussed are the partitioning of fatty acid precursors into wax biosynthesis and the elongation of fatty acids with particular emphasis on the nature of the acyl primer, and the role of ATP in fatty acid elongation. The recent cloning of wax biosynthetic genes and the transport of wax to plant surfaces are also discussed.
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14
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Harwood JL. Recent advances in the biosynthesis of plant fatty acids. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1301:7-56. [PMID: 8652653 DOI: 10.1016/0005-2760(95)00242-1] [Citation(s) in RCA: 248] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- J L Harwood
- School of Molecular and Medical Biosciences, University of Wales, Cardiff, UK
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Cassagne C, Lessire R, Bessoule JJ, Moreau P, Creach A, Schneider F, Sturbois B. Biosynthesis of very long chain fatty acids in higher plants. Prog Lipid Res 1994; 33:55-69. [PMID: 8190743 DOI: 10.1016/0163-7827(94)90009-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- C Cassagne
- Institut de Biochimie Cellulaire, Bordeaux, France
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16
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Lessire R, Bessoule JJ, Cook L, Cinti DL, Cassagne C. Occurrence and characterization of a dehydratase enzyme in the leek icosanoyl-CoA synthase complex. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1169:243-9. [PMID: 7548117 DOI: 10.1016/0005-2760(93)90247-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The presence of a beta-hydroxyacyl-CoA dehydratase involved in the icosanoyl-CoA synthase (EC 2.3.1.119) complex of leek epidermis has been demonstrated using antibodies raised against the purified beta-hydroxyacyl-CoA dehydratase from rat liver. In a first step the leek icosanoyl-CoA synthase activity was measured in the presence of different amounts of this antibody, the results obtained showed a 75% inhibition of the activity using a 8:1 IgG/microsomal protein ratio, whereas only a weak diminution of the activity occurred using pre-immune IgG. The analysis of the reaction products after incubation in the presence of increasing IgG amounts showed a decrease of the fatty acids (the final product) and an accumulation of beta-hydroxy fatty acids using immune IgG, whereas no change occurred in the presence of pre-immune IgG. Moreover, the beta-hydroxyacyl-CoA dehydratase activity was strongly inhibited, whereas in the same conditions, the beta-ketoacyl-CoA reductase and the (trans-2-3) enoyl-CoA reductase activities were not affected. The protein fractions that eluted from the DEAE and Ultrogel columns containing the leek icosanoyl-CoA synthase activity were able to specifically bind the anti beta-hydroxyacyl-CoA dehydratase from rat liver. The cross-reactivity was demonstrated. In immunoblotting experiments using the same antiserum after SDS-PAGE of the purified leek icosanoyl-CoA synthase, only one of the four protein bands constituting the leek icosanoyl-CoA synthase was detected. This protein, having an apparent molecular mass of 65 kDa, could be the dehydratase component of the elongation complex.
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Affiliation(s)
- R Lessire
- I.B.C.-CNRS, Université de Bordeaux II, France
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17
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Bessoule JJ, Creach A, Lessire R, Cassagne C. Evaluation of the amount of acyl-CoA elongases in leek (Allium porrum L) leaves. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1117:78-82. [PMID: 1627596 DOI: 10.1016/0304-4165(92)90165-q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Polyclonal antibodies have been raised against the acyl-CoA elongase purified from leek epidermal cells. The antibodies recognize the fractions containing the elongating activity after DEAE or Ultrogel chromatography and their response with the other fractions is very low. The immune complex is immunoprecipitable with Protein A-Sepharose. 1% of the solubilized proteins from leek epidermis microsomes are immunoprecipitated. The immunoprecipitate contains an elongating activity which is 86 +/- 20-times that of the unbound fraction.
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Affiliation(s)
- J J Bessoule
- Institut de Biochimie Cellulaire et Neurochimie du CNRS, Université de Bordeaux, France
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18
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Fehling E, Lessire R, Cassagne C, Mukherjee KD. Solubilization and partial purification of constituents of acyl-CoA elongase from Lunaria annua. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1126:88-94. [PMID: 1606179 DOI: 10.1016/0005-2760(92)90221-g] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
All the constituent enzymes of acyl-CoA elongase, i.e., beta-ketoacyl-CoA synthase, beta-ketoacyl-CoA reductase, beta-hydroxyacyl-CoA dehydrase and trans-2-enoyl-CoA reductase, have been solubilized from a 15,000 x g particulate fraction from developing seeds of honesty (Lunaria annua) using Triton X-100. All these activities were retained upon subsequent precipitation of the solubilized protein with polyethylene glycol and resuspension of the precipitate followed by ion exchange chromatography of the resulting protein on DEAE-cellulose. A 4.2-fold enrichment of the acyl-CoA elongase was thus obtained. Further chromatography of the DEAE fraction containing all the constituents of acyl-CoA elongase on Ultrogel yielded a major protein fraction exhibiting the activities of beta-ketoacyl-CoA synthase and beta-ketoacyl-CoA reductase only. Almost 30-fold purification of the beta-ketoacyl-CoA synthase was thus achieved. The beta-ketoacyl-CoA synthase was inhibited only at high concentrations of cerulenin, but at very low concentrations of iodoacetamide. Inhibition could be reduced by preincubation with thioesters, indicating that an enzyme thioester intermediate is involved in the condensation reaction of the acyl-CoA elongation.
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Affiliation(s)
- E Fehling
- Federal Centre for Cereal, Potato and Lipid Research, H.P. Kaufmann-Institute, Münster, Germany
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19
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Bertho P, Moreau P, Morré DJ, Cassagne C. Monensin blocks the transfer of very long chain fatty acid containing lipids to the plasma membrane of leek seedlings. Evidence for lipid sorting based on fatty acyl chain length. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1070:127-34. [PMID: 1751519 DOI: 10.1016/0005-2736(91)90154-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Delivery of newly synthesized fatty acids and lipids to the plasma membrane in leek seedlings via the endoplasmic reticulum (ER)-Golgi apparatus pathway is primarily by bulk transport (without sorting). However, pulse-chase experiments revealed kinetics of transport of lipids with VLCFA (very long chain fatty acids having more than 18 carbon atoms) in favor of a preferential transfer of these molecules to the plasma membrane. Use of monensin showed the accumulation of lipids in the Golgi apparatus and a related decrease of the amount of lipids transported to the plasma membrane. Lipid and fatty acid analyses revealed that transport of VLCFA-containing phospholipids was most strongly inhibited by the monensin block. These results taken together with an inability of the plasma membrane to synthesize VLCFA support a role for the Golgi apparatus in VLCFA delivery to the plasma membrane and leads to the hypothesis of a sorting function as well, based on fatty acyl chain length.
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Affiliation(s)
- P Bertho
- Institut de Biochimie et Neurochimie du CNRS, Université de Bordeaux II, France
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Fehling E, Mukherjee KD. Acyl-CoA elongase from a higher plant (Lunaria annua): metabolic intermediates of very-long-chain acyl-CoA products and substrate specificity. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1082:239-46. [PMID: 2029543 DOI: 10.1016/0005-2760(91)90198-q] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A particulate fraction (15,000 x g pellet) from developing seeds of honesty (Lunaria annua) was found to synthesize very-long-chain acyl-CoA thioesters in a manner similar to mammalian systems, i.e., via condensation of an acyl-CoA with malonyl-CoA yielding beta-ketoacyl-CoA, which is reduced to beta-hydroxyacyl-CoA, the latter dehydrated to trans-2-enoyl-CoA that is finally reduced to very-long-chain acyl-CoA. Reduced pyridine nucleotides (NADH/NADPH) are required for the reduction steps. In the absence of reduced pyridine nucleotides only the condensation reaction occurs. The acyl-CoA elongase does not exhibit any pronounced specificity for any of the saturated (14:0 to 20:0) or (n - 9)cis-monounsaturated (14:1 to 22:1) acyl-CoA substrates, although both the saturated and monounsaturated acyl-CoA substrates having chain lengths of C18 and C20 are elongated somewhat faster.
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Affiliation(s)
- E Fehling
- Federal Center for Lipid Research, H.P. Kaufmann-Institut, Müster, Germany
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Lessire R, Bessoule JJ, Cassagne C. Involvement of a β-ketoacyl-CoA intermediate in acyl-CoA elongation by an acyl-CoA elongase purified from leek epidermal cells. ACTA ACUST UNITED AC 1989. [DOI: 10.1016/0005-2760(89)90320-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bessoule JJ, Lessire R, Cassagne C. Theoretical analysis of the activity of membrane-bound enzymes using amphiphilic or hydrophobic substrates. Application to the acyl-CoA elongases from Allium porrum cells and to their purification. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1989. [DOI: 10.1016/0005-2736(89)90377-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Bessoule JJ, Lessire R, Cassagne C. Partial purification of the acyl-CoA elongase of Allium porrum leaves. Arch Biochem Biophys 1989; 268:475-84. [PMID: 2913944 DOI: 10.1016/0003-9861(89)90315-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Acyl-CoA elongase has been partially purified from leek (Allium porrum L.) epidermal cells. The microsomal elongase is first solubilized by Triton X-100. The solubilized proteins are then submitted to anion exchange chromatography on DEAE-cellulose and, finally, to gel filtration on Ultrogel 34 AcA. The purification of the elongase activity is accompanied by the enrichment in three major protein bands of 59, 61, and 65 kDa. The partially purified elongase is highly delipidated (about 10 mol lipid/mol of 60- to 65-kDa protein) and phosphatidylserine and phosphatidylethanolamine account respectively for 60 and 40% of the remaining phospholipids. The partially purified elongase retains some activities associated with fatty acid biosynthesis. The overall activity is strongly stimulated by the addition of exogenous lipids. In the presence of a mixture of PS, PE, and PC the C18-CoA elongase activity is increased more than sixfold. The Km value of stearoyl-CoA, in the presence of lipid vesicles, was determined to be 1.7 microM.
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Affiliation(s)
- J J Bessoule
- Institut de Biochimie Cellulaire et Neurochimie, Bordeaux, France
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Kolattukudy PE, Espelie KE. Chemistry, Biochemistry, and Function of Suberin and Associated Waxes. NATURAL PRODUCTS OF WOODY PLANTS 1989. [DOI: 10.1007/978-3-642-74075-6_11] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Bertho P, Moreau P, Juguelin H, Gautier M, Cassagne C. Monensin-induced accumulation of neosynthesized lipids and fatty acids in a Golgi fraction prepared from etiolated leek seedlings. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1989. [DOI: 10.1016/0005-2736(89)90503-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Walker KA, Harwood JL. Evidence for separate elongation enzymes for very-long-chain-fatty-acid synthesis in potato (Solanum tuberosum). Biochem J 1986; 237:41-6. [PMID: 3800889 PMCID: PMC1146945 DOI: 10.1042/bj2370041] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Aging potato (Solanum tuberosum) tuber discs in a Ca2+-containing medium resulted in increased rates of fatty acid labelling from [1-14C]acetate with time. Maximal labelling rates were seen after 6-8 h aging in a number of varieties. Saturated very-long-chain fatty acids (C20 and particularly C22 and C24) were very poorly labelled in freshly cut tissue. They were synthesized in increasing amounts and in a homologous sequence with progressive aging times. Use of increasing induction times and cycloheximide or puromycin as protein-synthesis inhibitors indicated that the sequence of fatty acid elongation was dependent on protein synthesis de novo and was controlled by three separate specific elongase enzymes.
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Elongation of (n−9) and (n−7)cis-monounsaturated and saturated fatty acids in seeds ofsinapis alba. Lipids 1986. [DOI: 10.1007/bf02535699] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Agrawal VP, Stumpf PK. Characterization and solubilization of an acyl chain elongation system in microsomes of leek epidermal cells. Arch Biochem Biophys 1985; 240:154-65. [PMID: 4015095 DOI: 10.1016/0003-9861(85)90018-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Microsomes prepared from leek epidermal tissue readily elongate stearoyl-CoA to very long chain fatty acid with malonyl-CoA as the C2 unit. In the absence of stearoyl-CoA, but in the presence of ATP, microsomes elongate endogenous free fatty acids. Endogenous CoA is the source of CoA. Palmitoyl, stearoyl, and higher saturated acyl-CoAs are readily elongated by the microsomal system but oleoyl-CoA is ineffective; however, the higher monounsaturated acyl-CoAs can be elongated. Since the very long chain fatty acids of the leek epidermis are all saturated, it would appear that the reaction controlling the nature of the final acyl product is the inactivity of oleoyl-CoA as a substrate. There is no evidence that acyl carrier protein participates in the elongation reactions. Evidence is also presented suggesting that (a) there may be two elongation systems, one responsible for the conversion of stearoyl-CoA to arachidonyl-CoA and the second involved in the conversion of arachidonyl-CoA to very long chain fatty acids, and that (b) the elongation activities may be associated with a large polypeptide.
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Walker KA, Harwood JL. Localization of chloroplastic fatty acid synthesis de novo in the stroma. Biochem J 1985; 226:551-6. [PMID: 3994672 PMCID: PMC1144743 DOI: 10.1042/bj2260551] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The synthesis of fatty acids de novo from [2-14C]malonyl-CoA was studied in fractions from lettuce (Lactuca sativa) and pea (Pisum sativum) chloroplasts. When lettuce chloroplasts were subjected to osmotic lysis, disintegration through a Yeda press and high-speed centrifugation, essentially all of the fatty-acid-synthetic activity was found to be soluble. The distribution of the activity in various chloroplast fractions was similar to that of soluble marker enzymes such as ribulose-1,5-bisphosphate carboxylase and NADP+-linked glyceraldehyde-3-phosphate dehydrogenase. Marked differences were apparent in the quality of products from fatty acid synthesis de novo in the various fractions of chloroplasts. Thus soluble fractions produced predominantly stearate, whereas those containing membranes produced a greater proportion of palmitate. In pea chloroplasts, osmotic lysis released almost all of the fatty acid synthetase into the stromal fraction. In this instance, no major alterations in the products of fatty acid synthesis were observed. The fatty-acid-synthetic activity of the stromal fraction was still soluble after prolonged ultracentrifugation. The results show clearly the soluble nature of fatty acid synthesis de novo in lettuce and pea chloroplasts. Thus fatty acid synthesis measured in microsomal fractions from such plant tissues is not due to the presence of chloroplastic membranes.
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Bognar AL, Paliyath G, Rogers L, Kolattukudy PE. Biosynthesis of alkanes by particulate and solubilized enzyme preparations from pea leaves (Pisum sativum). Arch Biochem Biophys 1984; 235:8-17. [PMID: 6497395 DOI: 10.1016/0003-9861(84)90249-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Enzymatic activity responsible for the conversion of fatty acids to alkanes catalyzed by pea leaf homogenate was found to be mainly in the microsomal fraction. This particulate preparation catalyzed alkane formation from n-C18, n-C22, and n-C24 acids at rates comparable to that observed with n-C32 acid with O2 and ascorbate as required cofactors. In each case the major alkane contained two carbon atoms less than the precursor acid. Since the preparation also catalyzed alpha-oxidation, it was suspected that some alpha-oxidation intermediate, with one less carbon atom than the substrate acid, might lose another carbon to generate the alkane. Thin-layer and radio-gas-liquid chromatographic analysis of the products generated from [U-14C]stearic acid by the particulate preparation after different periods of incubation showed that, at all time periods, alpha-hydroxy C18 acid, C17 aldehyde, and C17 acid were the major products. Since C16 alkane was the major product even after short periods of reaction, the C17 aldehyde might have been the immediate precursor of the alkane. Exogenous labeled C18 and C24 aldehyde were converted to alkanes. The alkane-synthesizing activity was solubilized from the microsomal preparation using Triton X-100. The solubilized preparation was retarded in a Sepharose 6-B column, but the hydrocarbon-forming activity was not resolved from alpha-oxidation. The solubilized preparation produced alkane with two carbon atoms less than the parent acid in a time- and protein-dependent manner. The soluble preparation also required O2 and ascorbate and, like the microsomal preparation, was inhibited by dithioerythritol and metal ion chelating agents.
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Agrawal VP, Lessire R, Stumpf PK. Biosynthesis of very long chain fatty acids in microsomes from epidermal cells of Allium porrum L. Arch Biochem Biophys 1984; 230:580-9. [PMID: 6712254 DOI: 10.1016/0003-9861(84)90438-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The elongation system present in leek epidermal cells functions to synthesize very long chain fatty acids which, in turn, are the precursors to alkanes. The elongation system is microsomal, employs only saturated acyl components of the endogenous lipid pool as acceptors, utilizes malonyl-CoA as the C2 donor, has an absolute requirement for ATP, and is markedly inhibited by acetyl-ACP. Only saturated acyl-CoAs are readily elongated to very long chain fatty acids by malonyl-CoA in the absence of ATP. ACP is not required by the microsomal system.
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Biosynthesis of esterified alkan-2-ols and β-diketones in barley spike epicuticular wax: Synthesis of radioactive intermediates. ACTA ACUST UNITED AC 1984. [DOI: 10.1007/bf02907782] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Sanchez J, Jordan BR, Kay J, Harwood JL. Lipase-induced alterations of fatty acid synthesis by subcellular fractions from germinating pea (Pisum sativum L.). Biochem J 1982; 204:463-70. [PMID: 7115342 PMCID: PMC1158373 DOI: 10.1042/bj2040463] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. The effect of exogenous lipases on fatty acid synthesis from [14C]malonyl-CoA by the microsomal and soluble fractions from germinating peas was studied. 2. Addition of phospholipase A2 or the lipase from Rhizopus arrhizus had no effect on total fatty acid synthesis by the soluble fraction but caused severe inhibition of that by the microsomal fraction. 3. The addition of enzymes with phospholipase activity particularly inhibited the microsomal stearate elongase. 4. Control studies indicated that the phospholipase-induced inhibition of fatty acid synthesis was due to the location of fatty acid synthetase, palmitate elongase and stearate elongase on the outside of the microsomal vesicles. 5. Experiments with a trypsin-like proteinase showed that approximately half the microsomal fatty acid synthesis was resistant to proteolysis. 6. Although addition of exogenous phospholipases had no effect on total fatty acid synthesis by the soluble fraction, it did increase alpha-hydroxylation of newly-formed palmitate and stearate. 7. The results provide further evidence for differences between the soluble and particulate fatty acid synthetase and palmitate elongase activities of germinating pea.
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Sanchez J, Harwood JL. Products of fatty acid synthesis by a particulate fraction from germinating pea (Pisum sativum L.). Biochem J 1981; 199:221-6. [PMID: 7337704 PMCID: PMC1163353 DOI: 10.1042/bj1990221] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The synthesis of lipids and acyl thioesters was studied in microsomal preparations from germinating pea (Pisum sativum cv. Feltham First) seeds. Under conditions of maximal synthesis (in the presence of exogenous acyl-carrier protein) acyl-acyl-carrier proteins accounted for about half the total incorporation from [14C]malonyl-CoA. Decreasing the concentrations of exogenous acyl-carrier protein lowered the overall synthesis of fatty acids by decreasing, almost exclusively, the radioactivity associated with acyl-acyl-carrier proteins. A time-course experiment showed that acyl-acyl-carrier proteins accumulated most of the radioactive label at the beginning of the incubation but, eventually, the amount of radioactivity in that fraction decreased, while a simultaneous increase in the acyl-CoA and lipid fractions was noticed. Addition of exogenous CoA (1 mM) produced a decrease of total incorporation, but an increase in the radioactivity incorporated into acyl-CoA. The microsomal preparations synthesized saturated fatty acids up to C20, including significant proportions of pentadecanoic acid and heptadecanoic acid. Synthesis of these 'odd-chain' fatty acids only took place in the microsomal fraction. In contrast, when the 18,000g supernatant (containing the microsomal and soluble fractions) was incubated with [14C]malonyl-CoA, the radioactive fatty acid and acyl classes closely resembled the patterns produced by germinating in the presence of [14C]acetate in vivo. The results are discussed in relation to the role of acyl thioesters in the biosynthesis of plant lipids.
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Abstract
The synthesis of fatty acids from [14C]malonyl-CoA was studied with a high-speed particulate fraction from germinating pea (Pisum sativum). The variety used (Feltham First) produced mainly saturated fatty acids with palmitate (30--40%) and stearate (40--60%) predominating. Several palmitate-containing lipids stimulated overall synthesis and, in addition, increased the percentage of label in stearate. The production of stearate was severely inhibited by preincubation of the microsomal fraction with snake venom phospholipase A2 or by incubation with Rhizopus arrhizus lipase. Addition of a series of di-saturated phosphatidylcholines, with different acyl constituents, resulted in stimulation of overall fatty acid synthesis as well as an increase in the radiolabelling of the fatty acid two carbon atoms longer than the acyl chain added. This chain lengthening of fatty acids donated from phosphatidylcholine was due to the action of both fatty acid synthetase and palmitate elongase. The latter would utilize dipalmitoyl phosphatidylcholine and was sensitive to arsenite whereas fatty acid synthetase would use dilauroyl phosphatidylcholine and was sensitive to cerulenin. The results are discussed in relation to previous data obtained in vivo on plant fatty acid synthesis and current suggestions for the role of phosphatidylcholine in this process.
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Lessire R, Cassagne C. Long chain fatty acid CoA-activation by microsomes from Allium porrum epidermal cells. ACTA ACUST UNITED AC 1979. [DOI: 10.1016/0304-4211(79)90005-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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